The NAACP of Maryland launched a radio ad Tuesday that features NAACP chairman emeritus Julian Bond urging voters to support Question 6, the referendum to uphold the new marriage equality law, because approving the measure “is the right thing to do.”

“I know a little something about fighting for what’s right and just,” says Bond in the ad, which will air in the Washington, D.C., and Baltimore markets, according to The Washington Post. “Maryland’s gay and lesbian families share the same values, and they should share in the right to marry,” he says.

Bond and the NAACP, whose national board endorsed marriage equality after President Barack Obama did, speak to the important African-American constituency in the solidly Democratic state. Blacks make up about one quarter of voters in Maryland, and while recent polling indicates that more than half of likely African-American voters support marriage equality, opponents are still trying to reach black voters through churches.

In the one-minute ad, Bond says the referendum is not an issue of religion but civil rights. Radio ads in North Carolina used a similar message in the weeks before voters ultimately passed a constitutional amendment to ban same-sex marriage and similar unions by a wide margin.

“I believe people of faith understand this isn’t about any one religious belief — it’s about protecting the civil right to make a lifelong commitment to the person you love,” says Bond.

The ad arrives as the campaign enters its final four heated weeks. Marriage equality opponents released their first TV ad on Monday with a focus on the “thousands of years” of marriage between men and women, and claims about marriage’s effect on the well-being of children. Advocates will begin to air ads Wednesday.